Improvement in slide-valves



^ aient utiiiiite.

ISAAC CRAFT, OF CINCINNATI, OHIO, ASSIGNOR TO HIMSEIlF, THOMAS J. WILLIAMAND CHARLES M. GREVE, OF SAME PLACE.

Letters Patent No. 97,887, dated December 1.4, 1869.

IMPROVEMENTIN SLIIJIEl-VZALV'ESi.`

The Schedule referred to in these Letters Patent and making part of the sama To all 4to whom it may concern:

Be it known thatI, ISAAC CRAFT, of Cincinnati,

Hamilton county, State of Ohio, have invented a `cer-A tain new arid usefulmprovement in Slide-Valves for Steam-Engines; and I do hereby declare the followin gto beaI sufficiently full, clear, and exact description thereof', to enable one skilled in the art to which my invention appertains, to make and use it, referencebeing had to the accompanying drawings, making part of this. speciticatiom My invention consists of certain devices by which g the steam is excluded from the upper face of the slidevalve, in order that the'same may be balanced, and `relieved from excessive friction by pressure lof steam, the devices-beingso constructed and arranged that there will be an equal expansion of metal in the valve and balancing-devices, to guard against the tightening of the valve, by expansion, between the seats when hot.

In the accompanying drawings Figure 1 is a longitudinal section of a valve-chamber and valve embodying my invention.

Figure 2 is a cross-section ofthe saine.

Figure 3 is a plan, *showing the device for the provision of steam-passages entirely round and abov'e the the valve and balancing-devices.

A is the valve-chest, of ordinary construct-ion, provided with steam-pipe B.- Y

C is the slide-valve, faced to a true face on both sides. Y

D D are the steam-ports, and

E, the exhaust-port of the cylindercasting F. The casting F is constructed with projecting wings `Gr G', which enclose the valve at the sides, making a loose'fit between the valve and wings.

Secured to these wings, on top, is a plate, H, which 'fits against the upper face ofthe valve.

The -bolts I serve to secure the plate H tothe wings G G', and the valve C slides snugly between the plate H and the valve-face on the cylinder.

Between the heads of the bolts I and the plate H, rubber gaskets, a, are inserted, which serve,.by their elasticity, to enable the valve to raise the plate H slightly in case the valve expands more than the wings G` G when hot.

Between the plateH and the wings G G', a rubberV gasket, b, (or copper gasket it' preferred) is inserted,

which permits of the plate being adjusted by the bolts I, in order to make the valve tit snugly between its faces, and to take up wear.

It will beseeu that the steam is admitted between the ordinary cover J and the plate H, and also', surrounds the wings G G entirely. This construction is designed to produce equal expansion of wings and valve, but if, from anycause, diiferent metals, or otherwise, the valve should expand more than the wings, the gaskets will permit it, without materially tightening the fit of the valve between the faces.

-By this device, the slidewalve is relieved from unequal pressure, and moves freely over its seat.

The provision of the gaskets provides against very tight iits'between the valve and double seats, and permits of the wear being taken up.

The wings G G' are shorter, as shown, than the valve-chest, in order to form passages at the ends for the steam to enter.

I claim herein as new and of myinventiou- 1. The combination of the wings G G', plate H, and bolts I, when the same are so constructed with relation to the steam-chest A J, as to be, when in use, surrounded exteriorly by steam, for the purpose speciiied. e

2. In the described combination, with the elements of thc preceding clause, the gaskets a b, arranged and operating substantially in the manner and for the purpose described. i

In testimony of which invention, I hereunto set my hand.

i his .ISAAC X CRAFT.

mark.

Witnesses:

FRANK MILLWARD, I. S. \`VARTMANN. 

